Feed rolls in rolling engagement with the periphery of a printer platen for trapping and feeding sheets of paper are well known and have been used extensively in the typewriter and printer art.
Recent examples of such mechanisms involving feed rolls are U.S. Pat. No. 4,215,945 and U.S. Pat. No. 4,221,489.
U.S. Pat. No. 4,215,945 to Habich, et al, discloses a paper feed roll assembly carrying, on the deflector, feed rolls for engagement with the platen periphery.
The particular feed roll/paper deflector disclosed in U.S. Pat. No. 4,215,945 is particularly adapted to rocking of the paper deflector and the extending of paper alignment fingers through the paper deflector for automated paper insertion.
The paper deflector, once positioned on a supporting shaft, is selectively engageable through the feed rolls with the platen by rocking the paper deflector to engage either the front or the back feed rolls. However, the assembly is incapable of self-alignment with the platen inasmuch as it is constrained by the support shaft.
The paper deflector feed roll truck disclosed in U.S. Pat. No. 4,215,945 is readily assembled with the remainder of the typewriter but does not teach any self-alignment of the feed rolls with respect to the platen and, thus, would require rigid manufacturing and assembly quality control.
U.S. Pat. No. 4,221,489 to Engle, et al, is substantially completely self-aligning. The assembly of this device requires that the paper release bail be installed into the typewriter frame after the feed roll trucks have all been assembled in the remainder of the typewriter frame and supports.
The device disclosed in U.S. Pat. No. 4,221,489 provides the desirable self-alignment feature but is not a design which will permit ready assembly by automated assembly apparatus and is somewhat cumbersome for removal of the feed roll trucks for servicing.